菱镁矿混合氯化镁焙烧制备高纯氧化镁

Preparation of high purity magnesia from calcining magnesite mixed magnesium chloride

采用菱镁矿添加无水氯化镁混合焙烧的方式,在较低焙烧温度下制备了高纯度的氧化镁。通过热重-差热(TG-DTA)法分析了菱镁矿的焙烧反应过程,并对焙烧产品进行了X射线衍射(XRD)、扫描电镜(SEM)及纯度分析。与传统焙烧方法制备氧化镁相比,添加氯化镁的焙烧工艺可有效地达到除钙效果。通过机理探讨表明,氯化镁渗透到菱镁矿中起隔断作用,有效增加了菱镁矿的比表面积,降低了焙烧温度,达到了节能降耗的效果。在焙烧温度为650℃、保温时间为1 h条件下,所得氧化镁的纯度可达99.3%,钙杂质质量分数可降至0.07%。

High-purity magnesium oxide was prepared by calcining magnesite which mixed with anhydrous magnesium chlo- ride at a lower calcination temperature.The thermal decomposition of mixed powders was analyzed by thermogravimetric anal- ysis and dynamic thermogravimetric analysis （TG-DTA）.The prepared product was also characterized by X-ray diffraction （XRD）, scanning electronic microscope （SEM）, and purity analysis.Compared with the traditional method, the results showed that adding magnesium chloride can effectively remove calcium.Through mechanism discussion,because of chloride ion＇s penetration,magnesium chloride played a role of partition to magnesite,it made magnesite＇s specific surface area increase and calcination temperature decrease,which got the effect of energy-saving and cost-reducing.The product＇s purity could reach 99.3% and calcium impurity mass fraction reduced to 0.07% ,when calcination temperature was 650 ℃ and calcination time was 1 h.